CN102539367A - Method for measuring content of protein nitrogen in liquid - Google Patents
Method for measuring content of protein nitrogen in liquid Download PDFInfo
- Publication number
- CN102539367A CN102539367A CN2011104601579A CN201110460157A CN102539367A CN 102539367 A CN102539367 A CN 102539367A CN 2011104601579 A CN2011104601579 A CN 2011104601579A CN 201110460157 A CN201110460157 A CN 201110460157A CN 102539367 A CN102539367 A CN 102539367A
- Authority
- CN
- China
- Prior art keywords
- liquid
- sample
- obtains
- tested
- protein
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention provides a method for measuring content of protein nitrogen in liquid, which includes the following steps: separating protein nitrogen in liquid to obtain a to-be-measured sample containing nonprotein nitrogen; adding potassium persulfate into the to-be-measured sample that is being heated to obtain a mixed solution; ultraviolet catalyzing and high-temperature heating the mixed solution sequentially to obtain a digestion product; measuring the digestion product to obtain the content of nonprotein nitrogen in the liquid; and obtaining the content of protein nitrogen in the liquid as per the predeterminate total nitrogen content in the liquid and the content of nonprotein nitrogen obtained through measurement. Through adopting the method provided by the invention, the nitrogenous component in the liquid can be radically and completely digested, the digestion effect is better, the nitrogenous component as well as the reducing component in the liquid are digested, so that the liquid loses the reducing action, the interference in the digestion of the nitrogenous component is reduced, the uniformity of the digestion result is improved, the recovery rate in the content measurement of the protein nitrogen is improved, and the accuracy of the testing result is improved.
Description
Technical field
The present invention relates to a kind of analysis determining technology field of protein nitrogen, relate in particular to the assay method of protein nitrogen content in a kind of liquid.
Background technology
Protein is the important substance that constitutes cell and biosome structure, the effect with catalysis, transportation, transmission information, and the vital movement that can regulate body, the enhancing body resistibility is regulated osmotic pressure, and heat supply plays crucial effects to vital movement.Sufficient protein can keep the normal vital sign of life entity, therefore, has great importance for the mensuration of protein content.
Each protein all has its constant nitrogen content; But because protein is formed and the complicacy of character, represent the content of protein nitrogen usually with total nitrogen content, also comprised nonprotein nitrogen in the protein nitrogen content that obtains; Be unfavorable for evaluation to the nitrogen substance quality; Also can give the lawless person with opportunity, in food, add nonprotein nitrogen class material and pretend to be protein nitrogen content, bring huge threat for the people's health; Therefore, the mensuration to true protein nitrogen content has great importance.
Mensuration for nitrogen content; Usually the method that adopts is nitrogen-containing compound wherein to be cleared up be nitrate; The nitrate that obtains quantitatively is reduced to nitrite; Utilize the character of nitrite and sulfanilamide (SN) and N-naphthylethylenediamine hydrochloride colour developing, adopt spectrophotometry to obtain nitrogen content wherein.As employing flow injection analyzers such as Zou Lin measured total nitrogen and total phosphorus in the water content (Zou Lin, Zhou Shengdong, Chen Wei. high-pressure digestion flow injection photometry measures total nitrogen and total phosphorus in the water simultaneously. Chinese water supply and drainage; 2009; 25 (22): 93～97.), its process is: under 110 ℃, water sample is cleared up for twice through alkaline potassium persulfate and sulfuric acid; The product of clearing up that obtains gets into total nitrogen, total phosphorus analytic system in the flow injection analyzer respectively, obtains the content of total nitrogen in the water sample, total phosphorus.In the total nitrogen analytic system; Clear up product through behind copper-plated cadmium circle, nitrate radical quantitatively is reduced to nitrite anions, under acid condition; Nitrite anions and sulfanilamide (SN) and N-naphthylethylenediamine hydrochloride react under 45 ℃ of constant temperatures and generate the aubergine material; Its optimum absorb wavelength is 550nm, adopts AAS that the aubergine material that obtains is measured, and obtains the total nitrogen content in the water.
Above-mentioned high-pressure digestion has the nitrogen-containing compound in the water body clears up effect preferably; Yet for the complicated liquid of constituent; Like milk etc.; The method of this high-pressure digestion is cleared up inadequately fully nitrogen containing components such as wherein some nitrogen substance such as vegetable soda, amino acid, some water soluble proteins and thoroughly, and what obtain clears up the product heterogeneity, gives to measure nitrogen content and brought bigger error; And also contain the reductibility composition in the liquid; Like carbohydrate; These reductibilities become branch and oxidant reaction, thereby influence makes the nitrogen-containing compound in the liquid clear up thorough inadequately to the clearing up of nitrogen component; Have a strong impact on the effect of clearing up, make inaccurate the mensuration result of protein nitrogen content in the liquid to nitrogen-containing compound in the liquid.
Summary of the invention
The object of the present invention is to provide the assay method of protein nitrogen content in a kind of liquid, method provided by the invention has high accuracy to the mensuration result of protein nitrogen in the liquid.
The present invention provides the assay method of protein nitrogen content in a kind of liquid, may further comprise the steps:
A) protein nitrogen in the separating liquid obtains containing the sample to be tested of nonprotein nitrogen;
B) under heating condition, in said sample to be tested, add potassium persulfate, obtain mixed solution;
C) said mixed solution is carried out ultraviolet catalytic and heat successively, obtain clearing up product;
D) detect the said product of clearing up, obtain non-protein nitrogen content in the liquid;
E) according to total nitrogen content in the predetermined said liquid and the non-protein nitrogen content that obtains, obtain protein nitrogen content in the liquid.
Preferably, said ultraviolet catalytic is for carrying out ultraviolet catalytic in the non-sulfuric acid sour environment.
Preferably, the temperature of said ultraviolet catalytic is 90 ℃～110 ℃.
Preferably, the temperature of said heat is 95 ℃～150 ℃.
Preferably, said heat is the pressurized high-temperature heating.
Preferably, the pressure of said pressurized high-temperature heating is 5Psi～8Psi.
Preferably, the heating-up temperature in the said step b) is 90 ℃～110 ℃.
Preferably, said step a) is specially:
In liquid, add protein denaturation reagent, heat the potpourri that obtains, obtain containing the sample to be tested of nonprotein nitrogen after the separation.
Preferably, said protein denaturation reagent is organic acid.
Preferably, also comprise before the said step b):
In said sample to be tested, add hydrogen peroxide, the reductibility component in the said sample to be tested of oxidation;
And/or in said sample to be tested, add activated charcoal, remove the inorganic pigment in the said sample to be tested;
And/or in said sample to be tested, add disodium ethylene diamine tetraacetate, remove the metallic ion in the said sample to be tested.
The present invention provides the assay method of protein nitrogen content in a kind of liquid, may further comprise the steps: the protein nitrogen in the separating liquid obtains containing the sample to be tested of nonprotein nitrogen; Under heating condition, in said sample to be tested, add potassium persulfate, obtain mixed solution; Said mixed solution is carried out ultraviolet catalytic and heat successively, obtain clearing up product; Detect the said product of clearing up, obtain non-protein nitrogen content in the liquid; According to total nitrogen content in the predetermined said liquid and the non-protein nitrogen content that obtains, obtain protein nitrogen content in the liquid.In the present invention; Potassium persulfate discharges active oxygen atom [O] under heating condition; The active oxygen atom that obtains [O] is tentatively cleared up fluid sample; Under the ultraviolet catalytic condition, part active oxygen atom [O] generates free radical with the water reaction under the ultraviolet catalytic condition then, and this free radical is cleared up the nitrogen substance in the sample; Then, under hot conditions, active oxygen atom [O] is further cleared up nitrogen substance, and wherein each type of nitrogen component cleared up fully.Method provided by the invention has also been cleared up reductibility component wherein when the nitrogen component in the liquid is cleared up; Make it lose reducing action; Eliminated of the interference of reductibility component to nitrogen analysis; Improved and cleared up homogeneity as a result, improved the recovery and accuracy that protein nitrogen in the liquid is detected.In addition, assay method provided by the invention has good stable property and repeatability.
Adopt method provided by the invention to measure protein nitrogen content in the milk, experimental result shows that method provided by the invention is accurate to the mensuration result of protein nitrogen in the milk.Method provided by the invention adopts the mode of clearing up continuously, clears up mild condition, and is simple to operate, save time, and step is easy, improve result's accuracy, and the batch processing sample capability is stronger, and the processing cycle is shorter, has improved detection efficiency greatly.
Description of drawings
The ultraviolet spectrogram that Fig. 1 obtains for the embodiment of the invention 1;
The non-linear secondary standard curve that Fig. 2 obtains for the embodiment of the invention 1;
The linear standard curve that Fig. 3 obtains for the embodiment of the invention 1.
Embodiment
The invention provides the assay method of protein nitrogen content in a kind of liquid, may further comprise the steps:
A) protein nitrogen in the separating liquid obtains containing the sample to be tested of nonprotein nitrogen;
B) under heating condition, in said sample to be tested, add potassium persulfate, obtain mixed solution;
C) said mixed solution is carried out ultraviolet catalytic and heat successively, obtain clearing up product;
D) detect the said product of clearing up, obtain non-protein nitrogen content in the liquid;
E) according to total nitrogen content in the predetermined said liquid and the non-protein nitrogen content that obtains, obtain protein nitrogen content in the liquid.
For the ease of the mensuration to protein nitrogen content in the liquid, the present invention preferably carries out pre-treatment to said liquid, specifically may further comprise the steps:
If contain insoluble impurities in the said liquid, like sewage, filter said liquid, remove insoluble impurities wherein, obtain filtrating; If nitrogen content is higher in the said liquid, the present invention more preferably 5～15 times, most preferably is 8～10 times preferably with 2～20 times of said liquid dilutings; If nitrogen content is lower in the said liquid, the present invention more preferably 5～15 times, most preferably is 8～10 times preferably with 2～20 times of said liquid concentration.
After said liquid carried out pre-treatment, the present invention separated the protein nitrogen in the said filtrating, obtains containing the sample to be tested of nonprotein nitrogen.
The present invention can adopt in said filtrating and to add protein denaturation reagent, the potpourri that heating obtains, or ultraviolet toasts the method for said filtrating, solidifies protein wherein, separates the protein after solidifying, and obtains containing the sample to be tested of nonprotein nitrogen; The present invention preferably adds protein denaturation reagent in said filtrating, the potpourri that heating obtains separates the protein after solidifying, and obtains containing the testing sample of nonprotein nitrogen, and said protein denaturation reagent is preferably organic acid, more preferably aqueous acetic acid; The volume fraction of said aqueous acetic acid is preferably 0.1%～5%, and more preferably 0.3%～4%, most preferably be 0.5%～3%; The volume ratio of said protein denaturation reagent and said fluid sample is 25: (0.1～3), more preferably 25: (0.3～1); Preferably with extremely boiling of the mixture heated that obtains; Be preferably 5 minutes said heat time heating time～50 minutes, more preferably 8 minutes～40 minutes, most preferably be 20 minutes～30 minutes.
After stopping heating, preferably with the solution filtered while hot that obtains, with the preferred drip washing of said protein denaturation reagent 1 time～10 times; More preferably 2 times～8 times, most preferably be 3～5 times, merge the filtrating that at every turn obtains; Cool off the back constant volume, obtain containing the sample to be tested of nonprotein nitrogen.
In order to reduce reductibility component in the fluid sample to the interference of wherein nitrogen analysis, the reductibility component before the present invention clears up said sample to be tested in the preferred said sample to be tested of oxidation.In the present invention, preferably in said sample to be tested, add hydrogen peroxide, the reductibility component in the said sample to be tested of oxidation.Reductibility component in said hydrogen peroxide and the said sample to be tested is carried out redox reaction; Make it lose reducing action; The mass concentration of said hydrogen peroxide is preferably 3%～50%, and more preferably 10%～30%, the present invention is to proportion of raw materials in the said redox reaction; Reaction conditionss etc. do not have particular restriction, are the redox reaction between reducing substances well known to those skilled in the art and the hydrogen peroxide.
In order to reduce the interference of impurity to nitrogen analysis; The present invention preferably removes the impurity in the said sample to be tested before said sample to be tested is cleared up, with the filtrating constant volume that obtains, obtain containing the sample to be tested of nonprotein nitrogen; When containing inorganic pigment in the said sample to be tested; Can adopt following method to handle: preferably in said filtrating, to add activated charcoal, filter the mixed solution that obtains, remove inorganic pigment wherein; When containing metallic ion in the said sample to be tested; Can adopt following method to handle: preferably in said filtrating, to add disodium ethylene diamine tetra-acetic acid solution; The mixed solution that filtration obtains is removed metallic ion wherein, and the concentration of said disodium ethylene diamine tetra-acetic acid solution is preferably 0.1g/L～5g/L; More preferably 0.2g/L～3g/L most preferably is 0.8g/L～2g/L; When containing inorganic pigment and metallic ion in the said sample to be tested, can remove inorganic pigment with said method earlier and remove metallic ion again, also can remove metallic ion with said method earlier and remove inorganic pigment again.
After obtaining containing the sample to be tested of nonprotein nitrogen, the present invention adds potassium persulfate in said sample to be tested under heating condition, obtain mixed solution.Said potassium persulfate discharges active oxygen atom [O] under heating condition, the active oxygen atom that obtains is cleared up the nitrogen component in the sample to be tested, obtains clearing up product.The quality of said potassium persulfate and the volume ratio of said liquid are preferably 1g: (1～20) mL, more preferably 1g: (2～15) mL most preferably is 1g: (3～10) mL; Preferably in said sample to be tested, add potassium persulfate solution, the volumetric molar concentration of said potassium persulfate solution is preferably 0.1mol/L～1mol/L, and more preferably 0.15mol/L～0.8mol/L most preferably is 0.25mol/L～0.5mol/L; Said heating-up temperature is preferably 90 ℃～110 ℃, more preferably 95 ℃～105 ℃.
After obtaining mixed solution, the present invention carries out ultraviolet catalytic and heat successively with said mixed solution, obtains the product of clearing up of sample to be tested.
At first said mixed solution is carried out ultraviolet catalytic, obtain the product of clearing up of ultraviolet catalytic.In the ultraviolet catalytic process; The above-mentioned part active oxygen atom [O] that obtains reacts with water under the condition of ultraviolet catalytic; Preferably under the ultra violet lamp condition; Generate free radical, said free radical can be cleared up the reductibility components such as all kinds of organic nitrogens in the sample to be tested, obtains the product of clearing up of ultraviolet catalytic.Said ultraviolet catalytic preferably carries out ultraviolet catalytic in the non-sulfuric acid sour environment, more preferably in the hydrochloric acid sour environment, carry out ultraviolet catalytic; The temperature of said ultraviolet catalytic is preferably 90 ℃～110 ℃, more preferably 95 ℃～105 ℃.
Obtain ultraviolet catalytic clear up product after, the present invention proceeds heat with the product of clearing up of said ultraviolet catalytic, obtains the product of clearing up of said sample to be tested.In high-temperature heating process, the above-mentioned active oxygen atom that obtains [O] product of clearing up to said ultraviolet catalytic under hot conditions is further cleared up, and obtains the product of clearing up of said testing sample.The temperature of said heat is preferably 95 ℃～150 ℃, more preferably 100 ℃～140 ℃, most preferably is 110 ℃～130 ℃; Said heat is preferably the pressurized high-temperature heating, and the pressure of said pressurized high-temperature heating is preferably 5Psi～8Psi, more preferably 5.5Psi～7.5Psi.
Obtain said sample to be tested clear up product after, detect the said product of clearing up, the present invention preferably adopts ultraviolet spectrophotometry to detect the said product of clearing up, and obtains the said ultraviolet spectrum data of clearing up product.The product of clearing up that at first will obtain reduces; Obtain nitrite; Then said nitrite is preferably reacted with sulfanilamide (SN) and N-(1-naphthyl) ethylenediamine dihydrochloride; Obtain the aubergine product, the aubergine product that adopts determined by ultraviolet spectrophotometry to obtain obtains the said ultraviolet spectrum data of clearing up product.The product of clearing up that preferably will obtain with cadmium reduces, and obtains nitrite; The concentration of said sulfanilamide (SN) is preferably 1g/L～50g/L, and more preferably 10g/L～40g/L most preferably is 20g/L～30g/L; The concentration of said N-naphthylethylenediamine hydrochloride is preferably 0.1g/L～10g/L, and more preferably 0.5g/L～8g/L most preferably is 1g/L～5g/L; Said mensuration wavelength is preferably 520nm～560nm, and more preferably 530nm～550nm most preferably is 535nm～545nm.
Ultraviolet spectrum data and predetermined typical curve according to technique scheme obtains can obtain non-protein nitrogen content in the liquid.
In the present invention, said typical curve preferably obtains according to following method:
The standard solution of preparation series concentration;
Under heating condition, in said standard solution, add potassium persulfate, obtain mixed solution;
Said mixed solution is carried out ultraviolet catalytic and heat successively, obtain clearing up product;
Detect the said product of clearing up, obtain the ultraviolet spectrum data of series concentration standard solution;
According to said ultraviolet spectrum data drawing standard curve.
Standard solution is preferably sodium nitrate aqueous solution described in the present invention, adopts the nitrate nitrogen standard of State Standard Matter Research Centre, the standard solution of preparation series concentration.At first, prepare the storing solution of standard substance, the storing solution that obtains is diluted to the concentration of standard solution.The mass concentration of said standard solution is preferably 0.001%～10%, and more preferably 0.01%～5%, most preferably be 0.1%～1%; Preferably with acetum the standard substance storing solution is diluted to the concentration of standard solution, the volume fraction of said acetum is preferably 0.1%～10%, and more preferably 0.25%～8%, most preferably be 0.5%～5%.
After obtaining the standard solution of series concentration, the present invention adds potassium persulfate in the said standard solution under heating condition, obtain mixed solution.Said potassium persulfate discharges active oxygen atom [O] under heating condition, the active oxygen atom that obtains [O] can be cleared up said standard solution, obtains clearing up product.The mass ratio of standard substance is preferably 1 in said potassium persulfate and the said standard solution: (1～20), and more preferably 1: (2～15) most preferably are 1: (3～10); Preferably in said standard solution, add potassium persulfate solution, the volumetric molar concentration of said potassium persulfate solution is preferably 0.1mol/L～1mol/L, and more preferably 0.15mol/L～0.8mol/L most preferably is 0.25mol/L～0.5mol/L; Said heating-up temperature is preferably 90 ℃～110 ℃, more preferably 95 ℃～105 ℃.
After obtaining mixed solution, the present invention carries out ultraviolet catalytic and heat successively with said mixed solution, obtains clearing up product.Said ultraviolet catalytic and high-temperature heating process are identical with ultraviolet catalytic and high-temperature heating process in the technique scheme.
According to ultraviolet catalytic in the technique scheme and high-temperature heating process, after obtaining clearing up product, detect the said product of clearing up, obtain the ultraviolet spectrum data of series concentration standard solution.Said testing process is identical with testing process in the technique scheme.
According to the testing process in the technique scheme, obtain the ultraviolet spectrum data of series concentration standard solution after, according to said ultraviolet spectrum data and corresponding concentration drawing standard curve thereof.Said typical curve is preferably non-linear secondary standard curve or linear standard curve.
The fluid sample that obtains according to technique scheme is cleared up the ultraviolet spectrogram and the typical curve of product; Through calculating the quality of nonprotein nitrogen in the liquid; With the quality of said nonprotein nitrogen quality or volume, obtain non-protein nitrogen content in the liquid again divided by aforesaid liquid.
Obtain in the liquid behind the non-protein nitrogen content, deduct non-protein nitrogen content in the said liquid, obtain non-protein nitrogen content in the liquid with total nitrogen content in the predetermined liquid.Among the present invention; Can adopt the method for non-protein nitrogen content in the said determination liquid to measure total nitrogen content in the liquid; Also can adopt total nitrogen content in continuous flow method, distillation titrimetry, ammonia gas-sensing electrode method or the ion-chromatographic determination liquid; The present invention does not have particular restriction to said continuous flow method, distillation titrimetry, ammonia gas-sensing electrode method or the chromatography of ions, is continuous flow method well known to those skilled in the art, distillation titrimetry, ammonia gas-sensing electrode method or the chromatography of ions.
When adopting the method for non-protein nitrogen content in the said determination liquid to measure in the liquid total nitrogen content; The difference of the technical scheme that non-protein nitrogen content is measured in technical scheme that total nitrogen content is measured in the said liquid and the aforesaid liquid is; The mensuration of total nitrogen content does not comprise the protein nitrogen in the step a) separating liquid in the liquid, obtains containing the sample to be tested of nonprotein nitrogen.
Obtain in the liquid deducting non-protein nitrogen content with total nitrogen content in the said liquid behind the total nitrogen content and non-protein nitrogen content, obtain protein nitrogen content in the liquid.
Obtain in the liquid behind the protein nitrogen content, the present invention also comprises according to protein nitrogen content and calculates protein content in the liquid, and said protein nitrogen content multiply by protein factor, can obtain the protein content in the liquid.
In liquid provided by the invention in the assay method of protein nitrogen content; Potassium persulfate discharges active oxygen atom [O]; The active oxygen atom that obtains [O] carries out tentatively clearing up to sample to be tested, under ultraviolet catalytic and hot conditions, fluid sample is cleared up further successively then, makes nitrogen substance wherein clear up more fully and up hill and dale; And eliminated the influence that reductibility component wherein offsets hydrolysis products; Have the good effect of clearing up, improved the homogeneity of clearing up product, the result that method provided by the invention is measured protein nitrogen content in the liquid accurately and reliably.Experimental result shows that method provided by the invention is accurate to the mensuration result of protein nitrogen content in the milk.In addition, method provided by the invention has good stable property and repeatability.
In order to further specify the present invention, below in conjunction with embodiment the assay method of protein nitrogen content in the liquid provided by the invention is described in detail, but can not they be interpreted as the qualification to the bright protection domain of this law.
11g sodium nitrate is dissolved in the 100mL distilled water, obtains mass concentration and be 10.0% sodium nitrate storing solution.Accurately pipette 1.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL, the said standard reserving solution of 10.0mL, use volume fraction be 0.5% acetum respectively with its constant volume to 100mL, obtain the sodium nitrate standard solution to be measured of series concentration.Get said standard solution 2mL to be measured respectively, the difference replicate determination is three times in the impouring Continuous Flow Analysis appearance sample hose, gets its mean value.In the Continuous Flow Analysis appearance, the sample feeding amount is 0.1mL/min, and sample injection time is 100s, and flush time is 120s.At first under 90 ℃; In said standard solution to be measured, adding the 2mL volumetric molar concentration is the potassium persulfate solution of 0.3mol/L; The sample size of potassium persulfate solution is 0.8mL/min, and the mixed solution that obtains then carries out ultra violet lamp 3min under the acid condition that 90 ℃, hydrochloric acid provide, the ultraviolet catalytic that then heat obtains under 6Psi pressure clear up product 2.5min; Heating-up temperature is 110 ℃, obtains the product of clearing up of sample.Clearing up when product passes through the cadmium post of obtaining is reduced to nitrite, gets into detecting device and carries out determined by ultraviolet spectrophotometry, and the detection wavelength is 540nm, obtains the ultraviolet spectrogram of standard substance.
The ultraviolet spectrogram of standard substance is as shown in Figure 1, and the ultraviolet spectrogram that Fig. 1 obtains for the embodiment of the invention 1, the signal fork among the figure on the curve are followed successively by the electrical signal intensity of the standard solution of series concentration since the 5th back to back 6 signals fork.Draw according to the ultraviolet spectrogram of the standard substance of the series concentration that obtains and corresponding concentration thereof and to obtain typical curve; As shown in Figures 2 and 3; The non-linear secondary standard curve that Fig. 2 obtains for the embodiment of the invention 1, the linear standard curve that Fig. 3 obtains for the embodiment of the invention 1, the nitrate concentration range of linearity of linear standard curve shown in Figure 3 is 0.1%～1%; Linear equation is: A (absorbance)=-1076.98+47750.43C (%), correlation coefficient r is 0.9981.In scheming, can find out that method provided by the invention obviously improves the electrical signal intensity that nitrogen analysis obtains, and have good linear relationship between electrical signal intensity and its concentration, method provided by the invention has good effect.
Comparative example 1
11g sodium nitrate is dissolved in the 100mL distilled water, obtains mass concentration and be 10.0% sodium nitrate storing solution.Accurately pipette 1.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL, the said standard reserving solution of 10.0mL, use volume fraction be 0.5% acetum respectively with it to 100mL, obtain the sodium nitrate standard solution of series concentration.The standard solution 2mL that obtains respectively, the difference replicate determination is three times in the impouring Continuous Flow Analysis appearance sample hose, gets its mean value.In the Continuous Flow Analysis appearance, the sample feeding amount is 0.1mL/min, and sample injection time is 100s, and flush time is 120s.At first under 90 ℃; In said standard solution, adding the 2mL volumetric molar concentration is the potassium persulfate solution of 0.3mol/L; The sample size of potassium persulfate solution is 0.8mL/min; The mixed solution 2.5min that heat obtains under 6Psi pressure then, heating-up temperature is 110 ℃, obtains the product of clearing up of sample.Clearing up when product passes through the cadmium post of obtaining is reduced to nitrite, gets into detecting device and carries out the ultraviolet spectrophotometry detection, and the detection wavelength is 540nm, obtains the ultraviolet spectrogram of standard substance.
Draw according to the ultraviolet spectrogram of the standard substance of the series concentration that obtains and to obtain typical curve.
Embodiment 2～6
Select 5 kinds of milk sample 2mL respectively, the said milk sample Te Lunsu of Mongolia Ox, the date of manufacture is respectively 20111010,20111022,20111031,20111115,20111118.To wherein adding the 50mL volume fraction is 0.5% acetic acid solution, and ebuillition of heated 15 minutes is rapidly with no nitrogen qualitative filter paper filtration; The use volume fraction is 0.5% acetic acid solution flushing sediment; Merge the filtrating that obtains, cooling back constant volume obtains the solution to be measured of milk to 200mL.Pipette the solution 2mL to be measured of said milk, the difference replicate determination is three times in the impouring Continuous Flow Analysis appearance sample hose, gets its mean value.In the Continuous Flow Analysis appearance, the sample feeding amount is 0.1mL/min, and sample injection time is 100s, and flush time is 120s.At first under 90 ℃; In the solution to be measured of said milk, adding the 2mL volumetric molar concentration is the potassium persulfate solution of 0.3mol/L; The sample size of potassium persulfate solution is 0.8mL/min, and the mixed solution that obtains then carries out ultra violet lamp 3min at the acid condition that 90 ℃, hydrochloric acid provide, the ultraviolet catalytic that then heat obtains under 6Psi pressure clear up product 2.5min; Heating-up temperature is 110 ℃, obtains the product of clearing up of sample.Clearing up when product passes through the cadmium post of obtaining is reduced to nitrite, gets into detecting device and carries out determined by ultraviolet spectrophotometry, and the detection wavelength is 540nm, obtains the ultraviolet spectrogram of milk sample.
The typical curve that obtains according to the ultraviolet spectrogram and the embodiment 1 of the milk sample that obtains is through calculating the non-protein nitrogen content in the milk sample.
Get the 2mL milk sample and be diluted to 200mL, obtain the solution to be measured of milk.Pipette the solution 2mL to be measured of said milk, the difference replicate determination is three times in the impouring Continuous Flow Analysis appearance sample hose, gets its mean value.In said mensuration process and the present embodiment in the milk mensuration process of non-protein nitrogen content identical, obtain the ultraviolet spectrogram of total nitrogen in the milk.
The typical curve that obtains according to the ultraviolet spectrogram and the embodiment 1 of total nitrogen in the milk that obtains is through calculating the total nitrogen content in the milk sample.
Total nitrogen content in the milk sample that obtains is deducted the non-protein nitrogen content in the above-mentioned milk that obtains, obtain the protein nitrogen content in the milk sample.The result is as shown in table 1, the mensuration result that table 1 obtains for the embodiment of the invention 2～6 and comparative example 2～6.
Comparative example 2～6
Select 5 kinds of milk sample 2mL respectively, milk sample used among said milk sample and the embodiment 2～6 is identical.To wherein adding the 50mL volume fraction is 0.5% acetic acid solution, and ebuillition of heated 15 minutes is rapidly with no nitrogen qualitative filter paper filtration; The use volume fraction is 0.5% acetic acid solution flushing sediment; Merge the filtrating that obtains, cooling back constant volume obtains the solution to be measured of milk to 200mL.Pipette said 2mL, the difference replicate determination is three times in the impouring Continuous Flow Analysis appearance sample hose, gets its mean value.In the Continuous Flow Analysis appearance, the sample feeding amount is 0.1mL/min, and sample injection time is 100s, and flush time is 120s.At first under 90 ℃; In the solution to be measured of said milk, adding the 2mL volumetric molar concentration is the potassium persulfate solution of 0.3mol/L; The sample size of potassium persulfate solution is 0.8mL/min; The mixed solution 2.5min that heat obtains under 6Psi pressure then, heating-up temperature is 110 ℃, obtains the product of clearing up of sample.Clearing up when product passes through the cadmium post of obtaining is reduced to nitrite, gets into detecting device and carries out the ultraviolet spectrophotometry detection, and the detection wavelength is 540nm, obtains the ultraviolet spectrogram of milk sample.
The typical curve that obtains according to the ultraviolet spectrogram and the embodiment 1 of the milk sample that obtains is through calculating the non-protein nitrogen content in the milk sample.
Get the 2mL milk sample and be diluted to 200mL, obtain the solution to be measured of milk.Pipette the solution 2mL to be measured of said milk, the difference replicate determination is three times in the impouring Continuous Flow Analysis appearance sample hose, gets its mean value.In said mensuration process and this comparative example in the milk mensuration process of non-protein nitrogen content identical, obtain the ultraviolet spectrogram of total nitrogen in the milk.
The typical curve that obtains according to the ultraviolet spectrogram and the embodiment 1 of total nitrogen in the milk that obtains is through calculating the total nitrogen content in the milk sample.
Total nitrogen content in the milk sample that obtains is deducted the non-protein nitrogen content in the above-mentioned milk that obtains, obtain the protein nitrogen content in the milk sample.The result is as shown in table 1, the mensuration result that table 1 obtains for the embodiment of the invention 2～6 and comparative example 2～6.
The mensuration result that table 1 embodiment of the invention 2～6 and comparative example 2～6 obtain
Annotate: protein nitrogen content * is a mass percent.
Can know that by table 1 method provided by the invention is accurate to the mensuration result of protein nitrogen content in the liquid, and the coefficient of variation of the data that obtain meets the requirement of analyzing and testing all less than 5%.
Can know that by above embodiment method provided by the invention is accurate to the result that the mensuration of protein nitrogen content in the liquid obtains.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; Can also make some improvement and retouching, these improvement and retouching also should be regarded as protection scope of the present invention.
Claims (10)
1. the assay method of protein nitrogen content in the liquid may further comprise the steps:
A) protein nitrogen in the separating liquid obtains containing the sample to be tested of nonprotein nitrogen;
B) under heating condition, in said sample to be tested, add potassium persulfate, obtain mixed solution;
C) said mixed solution is carried out ultraviolet catalytic and heat successively, obtain clearing up product;
D) detect the said product of clearing up, obtain non-protein nitrogen content in the liquid;
E) according to total nitrogen content in the predetermined said liquid and the non-protein nitrogen content that obtains, obtain protein nitrogen content in the liquid.
2. assay method according to claim 1 is characterized in that, said ultraviolet catalytic is for carrying out ultraviolet catalytic in the non-sulfuric acid sour environment.
3. assay method according to claim 1 is characterized in that, the temperature of said ultraviolet catalytic is 90 ℃～110 ℃.
4. assay method according to claim 1 is characterized in that, the temperature of said heat is 95 ℃～150 ℃.
5. assay method according to claim 1 is characterized in that, said heat is the pressurized high-temperature heating.
6. assay method according to claim 5 is characterized in that, the pressure of said pressurized high-temperature heating is 5Psi～8Psi.
7. assay method according to claim 1 is characterized in that, the heating-up temperature in the said step b) is 90 ℃～110 ℃.
8. assay method according to claim 1 is characterized in that, said step a) is specially:
In liquid, add protein denaturation reagent, heat the potpourri that obtains, obtain containing the sample to be tested of nonprotein nitrogen after the separation.
9. assay method according to claim 8 is characterized in that, said protein denaturation reagent is organic acid.
10. assay method according to claim 1 is characterized in that, also comprises before the said step b):
In said sample to be tested, add hydrogen peroxide, the reductibility component in the said sample to be tested of oxidation;
And/or in said sample to be tested, add activated charcoal, remove the inorganic pigment in the said sample to be tested;
And/or in said sample to be tested, add disodium ethylene diamine tetraacetate, remove the metallic ion in the said sample to be tested.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110460157.9A CN102539367B (en) | 2011-12-30 | 2011-12-30 | Method for measuring content of protein nitrogen in liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110460157.9A CN102539367B (en) | 2011-12-30 | 2011-12-30 | Method for measuring content of protein nitrogen in liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102539367A true CN102539367A (en) | 2012-07-04 |
| CN102539367B CN102539367B (en) | 2014-09-03 |
Family
ID=46346796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110460157.9A Active CN102539367B (en) | 2011-12-30 | 2011-12-30 | Method for measuring content of protein nitrogen in liquid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102539367B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110736804A (en) * | 2019-12-06 | 2020-01-31 | 四川蓝城检测技术有限公司 | Method for measuring total nitrogen content based on ion chromatography technology |
| CN115508521A (en) * | 2022-11-22 | 2022-12-23 | 今麦郎饮品股份有限公司 | A nutrient content survey system for drink |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1869656A (en) * | 2006-06-16 | 2006-11-29 | 南京大学 | Combined investigating analysing method of sediment total nitrogen and phosphorus |
| CN101354349A (en) * | 2008-07-24 | 2009-01-28 | 广东中烟工业有限责任公司 | Method for measuring protein nitrogen content in tobacco |
| CN201335809Y (en) * | 2009-01-13 | 2009-10-28 | 长沙华时捷环保科技发展有限公司 | Device for on-line digesting and detecting total nitrogen content in solution |
| CN102253232A (en) * | 2010-05-21 | 2011-11-23 | 北京吉天仪器有限公司 | Automatic analyzer and analysis method for water soluble total phosphorus |
-
2011
- 2011-12-30 CN CN201110460157.9A patent/CN102539367B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1869656A (en) * | 2006-06-16 | 2006-11-29 | 南京大学 | Combined investigating analysing method of sediment total nitrogen and phosphorus |
| CN101354349A (en) * | 2008-07-24 | 2009-01-28 | 广东中烟工业有限责任公司 | Method for measuring protein nitrogen content in tobacco |
| CN201335809Y (en) * | 2009-01-13 | 2009-10-28 | 长沙华时捷环保科技发展有限公司 | Device for on-line digesting and detecting total nitrogen content in solution |
| CN102253232A (en) * | 2010-05-21 | 2011-11-23 | 北京吉天仪器有限公司 | Automatic analyzer and analysis method for water soluble total phosphorus |
Non-Patent Citations (1)
| Title |
|---|
| 雷立改，等: "水中总氮、总磷测定方法的研究进展", 《河北工业科技》, vol. 28, no. 1, 31 January 2011 (2011-01-31) * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110736804A (en) * | 2019-12-06 | 2020-01-31 | 四川蓝城检测技术有限公司 | Method for measuring total nitrogen content based on ion chromatography technology |
| CN115508521A (en) * | 2022-11-22 | 2022-12-23 | 今麦郎饮品股份有限公司 | A nutrient content survey system for drink |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102539367B (en) | 2014-09-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101634648B (en) | Method for detecting six trace sweetening agents in white spirit by ultra-high pressure liquid chromatography and time-of-flight mass spectrometry | |
| CN101701914A (en) | Analysis detection method for calcium element in ore | |
| CN107202836B (en) | Method for rapidly analyzing theanine content in fresh tea sample | |
| CN101294898A (en) | Method for measuring chromium content in smoke tipping paper | |
| CN113916858A (en) | Cr detection by using nitrogen-doped carbon quantum dot fluorescent probe6+Method (2) | |
| CN102507469A (en) | Method for determining lead content of cigarette paper | |
| CN101349639A (en) | Method for measuring mercury content in loading paper for cigarette | |
| CN108333276A (en) | A method of the identification adulterated honey of high fructose syrup | |
| CN111638265A (en) | Detection method for simultaneously determining bromine, iodine and phosphorus in water sample or beverage by utilizing ICP-MS (inductively coupled plasma-mass spectrometry) | |
| CN101294897A (en) | Method for measuring nickel content in smoke tipping paper | |
| CN104614370A (en) | Quick nitrite detection method based on nanogold | |
| CN102539367B (en) | Method for measuring content of protein nitrogen in liquid | |
| CN102565425B (en) | Method for measuring protein nitrogen content in tobaccos | |
| CN102768191A (en) | Method for easily detecting trace thallium in water | |
| CN111189956A (en) | By means of H2O2Method for detecting content of nitrite in sodium chloride sample by combining oxidation method with ion chromatography | |
| Andac et al. | Flow-injection spectrophotometric determination of cobalt (II) at low μg l− 1 levels with 4-benzylpiperidinedithiocarbamate | |
| CN102519901A (en) | Method for measuring nonprotein nitrogen content in liquid | |
| CN101592644B (en) | Method for detecting barium ions in oil field water | |
| CN115260509A (en) | Boric acid functionalization based multi-emission metal organic framework compound Eu-MOF and application thereof in gallic acid detection | |
| CN210465266U (en) | Device for detecting nitrate in sugar | |
| CN101587128B (en) | Special ammonia indicator for analyzing ammonia content by flow injection instruments and preparation thereof | |
| CN102519899A (en) | Method for measuring total nitrogen content in liquid | |
| CN105806801A (en) | Method for detecting potassium sorbate in dairy product | |
| CN104749304A (en) | Method for determining concentrations of cyanide ion and sulfide ion in desulphurization solution | |
| CN103698293A (en) | Method for detecting cadmium of enzyme preparation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |